Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: l_d_allan on March 16, 2013, 03:23:43 pm
-
I was looking at the i1Profiler's 1.4.2 (demo) CCSG RGB values for scanners, and noticed what seem to be strange RGB values ... negatives and numbers > 255.
NUMBER_OF_SETS 140
BEGIN_DATA
15 B5 -45.00 121.00 193.00
16 B6 -29.00 155.00 184.00
17 B7 -5.00 51.00 50.00
18 B8 -25.00 157.00 157.00
......
126 M6 297.00 173.00 0.00
127 M7 271.00 189.00 -6.00
"Inquiring minds want to know" .... what's going on? A bug? Typo? Or some kind of code to the scanner about out-of-gamut? Special handling?
-
How did you find this file in i1Profiler? Give us the steps to duplicate what you found and we can take a look at it. This does look odd for RGB values.
-
My error ... the test-chart came from ProfileMakerPro 5.0.10 ...
"D ColorChecker SG Format.txt"
in the installed directory:
[Install-Dir]\Reference Files\Others
(also attached)
-
I don't have a very good answer, but I see the same thing in the scanner reference files as well as the camera references. And negative RGB values show up in the references for the regular ColorChecker too. All I can guess is that originally the references were made using something that applied RGB values to a certain gamut, and so the negative numbers and the >255 numbers represent what is outside of that gamut? Or something? ??? Check this out on Bruce Lindbloom's site:
http://www.brucelindbloom.com/index.html?ColorCheckerRGB.html